I have two 4x4's, both with 3.0 V6's. One is the stock truck engine and it consistently gets 17 to 19 around town for my landscape business. It doesn't seem to matter much if it's empty or has a ton of stone in the bed. I drove over to Spokane on the interstate at 75 and got about 14 mpg but came back on a two lane highway doing 60 and got nearly 21. The other truck has the higher compression version of the 6G72, a low mileage Japanese import from a Diamonte, and I have gotten as high as 24 mpg doing 70 on a road trip. This was coming back from Pullman, which is a pretty flat drive with altitude loss, which I am sure helped.